Grayscale Compensation Method and System for Defect on Display Panel

ABSTRACT

A method of grayscale compensation to defects on a display panel includes: (A) obtaining a set of coordination of the defect on the display panel, and determining a defect area where the defect locates based on the set of coordination; (B) obtaining a gamma curve of the defect, a gamma curve of a background of the defect area, and a standard gamma curve of the background of the display panel; (C) obtaining a standard gamma curve of the defect and a standard gamma curve of the background of the defect area; and (D) calculating a grayscale-compensation value for each grayscale of the defect, based on the standard gamma curve and the standard gamma curve of the background of the defect area. The present invention is to reduce calculation, and to achieve the best compensation to defects on a display panel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to manufacturing field of display panel,more particularly, to a method for grayscale compensation to defects ona display panel and a grayscale compensation system.

2. Description of the Prior Art

With fast developments in field of display panel, such display panelsperforming high-quality images as liquid crystal display panels ororganic light display panels have been mainstream products in markets.In current manufacturing field of display panel, procedural or materialinsufficiency causes to defects in spot, line, stripe and block forms ona display panel, which is very difficult to completely avoid.

Some defects, like compensable defects, can be cured by alteringexternal circuit voltage, or by changing amounts of digital grayscale,making the compensable defects perform as almost equal to normal areas.However, it is much larger for calculation by current method forgrayscale compensation to defects of display panel. The same method isunable to achieve the best compensation to the defect.

SUMMARY OF THE INVENTION

According to the present invention, a method of grayscale compensationto defects on a display panel comprises: (A) obtaining a set ofcoordination of the defect on the display panel, and determining adefect area where the defect locates based on the set of coordination;(B) obtaining a gamma curve of the defect, a gamma curve of a backgroundof the defect area, and a standard gamma curve of the background of thedisplay panel; (C) obtaining a standard gamma curve of the defect and astandard gamma curve of the background of the defect area, based on thegamma curve of the defect, the gamma curve of the background of thedefect area, and the standard gamma curve of the background of thedisplay panel; and (D) calculating a grayscale-compensation value foreach grayscale of the defect, based on the standard gamma curve and thestandard gamma curve of the background of the defect area.

In one aspect of the present invention, the step (C) of obtaining astandard gamma curve of the defect and a standard gamma curve of thebackground of the defect area comprises: obtaining a first mapping curveof a brightness value of the defect and a brightness value of thebackground of the display panel, and a second mapping curve of abrightness value of the background of the defect area and the brightnessvalue of the background of the display panel, based on the gamma curveof the defect, the gamma curve of the background of the defect area, andthe standard gamma curve of the background of the display panel; andobtaining the standard gamma curve of the defect and the standard gammacurve of the background of the defect area by the first mapping curveand the second mapping curve.

In another aspect of the present invention, before step (D), the methodfurther comprises: determining if the defect is a compensable defect. Incase that the defect as a compensable defect, performing step (D).

In still another aspect of the present invention, a step of determiningif the defect is a compensable defect comprises: determining the defectas a compensable defect, if a brightness value corresponding to amaximum grayscale of the standard gamma curve of the defect and aminimum grayscale of the standard gamma curve of the defect meetEquation 1

$\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where max denotes to the maximum grayscale of the standard gamma curveof the defect, min to the minimum grayscale of the standard gamma curveof the defect, X(max) to the brightness value corresponding to themaximum grayscale, X(min) to the brightness value corresponding to theminimum grayscale, and T to a predetermined threshold.

In yet another aspect of the present invention, the step (D) ofcalculating the grayscale compensation value of each grayscale based onthe standard gamma curve of the defect and the standard gamma curve ofthe background of the defect area, is performed by Equation 2

Δgray=gray2(L)−gray1(L),  Equation 2:

where gray1(L) denotes to a grayscale of the defect obtained at aparticular brightness value L based on the standard gamma curve of thedefect, gray2(L) to a grayscale of the background of the defect areaobtained at the particular brightness value L based on the standardgamma curve of the background of the defect area, and Δgray to agrayscale compensation value of the grayscale gray1(L) of the defect.

According to the present invention, a grayscale compensation system fora defect on a display panel comprises: a location obtaining unit,configured to obtain a set of coordination of the defect on the displaypanel, and to determine a defect area where the defect locates based onthe set of coordination; a gamma-curve obtaining unit, configured toobtain a gamma curve of the defect, a gamma curve of a background of thedefect area, and a standard gamma curve of the background of the displaypanel; a standard-gamma-curve obtaining unit, configured to obtain astandard gamma curve of the defect and a standard gamma curve of thebackground of the defect area, based on the gamma curve of the defect,the gamma curve of the background of the defect area, and the standardgamma curve of the background of the display panel; and a calculatingunit, configured to calculate a grayscale-compensation value for eachgrayscale of the defect, based on the standard gamma curve and thestandard gamma curve of the background of the defect area.

In one aspect of the present invention, the standard-gamma-curveobtaining unit is further configured to obtain a first mapping curve ofa brightness value of the defect and a brightness value of thebackground of the display panel, and a second mapping curve of abrightness value of the background of the defect area and the brightnessvalue of the background of the display panel, based on the gamma curveof the defect, the gamma curve of the background of the defect area, andthe standard gamma curve of the background of the display panel; and toobtain the standard gamma curve of the defect and the standard gammacurve of the background of the defect area by the first mapping curveand the second mapping curve.

In another aspect of the present invention, the grayscale compensationsystem further comprises: a compensable-defect determining unit,configured to determine if the defect is a compensable defect. In casethat the compensable-defect determining unit determines the defect as acompensable defect, the calculating unit calculates out thegrayscale-compensation value for each grayscale of the compensabledefect based on the standard gamma curve of the compensable defect andthe standard gamma curve of the background of the defect area whereinthe compensable defect located.

In still another aspect of the present invention, the compensable-defectdetermining unit further configured to determine the defect as acompensable defect if a brightness value corresponding to a maximumgrayscale of the standard gamma curve of the defect and a minimumgrayscale of the standard gamma curve of the defect meet Equation 1

$\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where max denotes to the maximum grayscale of the standard gamma curveof the defect, min to the minimum grayscale of the standard gamma curveof the defect, X(max) to the brightness value corresponding to themaximum grayscale, X(min) to the brightness value corresponding to theminimum grayscale, and T to a predetermined threshold.

In yet another aspect of the present invention, the calculating unitfurther configured to calculate out the grayscale compensation value ofeach grayscale, based on the standard gamma curve of the defect and thestandard gamma curve of the background of the defect area, by Equation 2

Δgray=gray2(L)−gray1(L),  Equation 2:

where gray1(L) denotes to a grayscale of the defect obtained at aparticular brightness value L based on the standard gamma curve of thedefect, gray2(L) to a grayscale of the background of the defect areaobtained at the particular brightness value L based on the standardgamma curve of the background of the defect area, and Δgray to agrayscale compensation value of the grayscale gray1(L) of the defect.

The object of the present invention is to substantially reducecalculation, and to achieve the best compensation to defects on adisplay panel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 depicts a flow chart of a method for grayscale compensation to adefect on a display panel according to a preferred embodiment of thepresent invention.

FIG. 2 depicts a block diagram of the grayscale compensation system forthe defect on the display panel according to another preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To be explained, the display panel illustrated in the preferredembodiment can be a liquid crystal display panel or an organic lightemitting display panel.

FIG. 1 depicts a flow chart of a method for grayscale compensation to adefect on a display panel according to a preferred embodiment of thepresent invention.

Referring to FIG. 1, at Step 110, it is to obtain a set of coordinationof a defect on a display panel, and to locate a defect area where thedefect locates based on a coordination of the defect. The method forobtaining the coordination of the defect on the display panel is:obtaining a brightness value of the defect on the display panel and thebrightness value of the background of the display panel, obtaining thecoordination of the defect on the display panel based on the brightnessvalue of the defect on the display panel and the brightness value of thebackground of the display panel; where the brightness value of thebackground of the display panel refers to a brightness value of a normalarea in the display panel, that is the non-defect area.

At Step 120, it is to obtain a gamma curve of the defect, a gamma curveof the defect area, and a standard gamma curve of the display panel. Thegamma curve of the defect can be obtained by a brightness value of eachgrayscale. The grayscale according to the preferred embodiment is from 0to 255, 256 grayscales in total. The gamma curve of the defect area canbe obtained by a brightness value of the background of the defect areaat each grayscale. The brightness value of the background of the defectarea refers to a brightness value of an area in rest of the defectwithin the defect area. The standard gamma curve of the display panelcan be obtained from the brightness value of the background of thedisplay panel measured by a standard optical measurement device (e.g. CA310) at each grayscale.

At Step 130, it is to obtain a standard gamma curve of the defect and astandard gamma curve of the background of the defect area based on thegamma curve of the defect, the gamma curve of the background of thedefect area and the standard gamma curve of the background of thedisplay panel.

A particular method for obtaining the standard gamma curve of the defectand the standard gamma curve of the background of the defect areacomprises:

To obtain a brightness value of the defect and a first mapping curve ofthe brightness value of the background of the display panel, and abrightness value of the background of the defect area and a secondmapping curve of the brightness value of the background of the displaypanel based on the gamma curve of the defect, the gamma curve of thebackground of the defect area, and the standard gamma curve of thebackground of the display panel; and to obtain a standard gamma curve ofthe defect and a standard gamma curve of the background of the defectarea by the first mapping curve and the second mapping curve.

At Step 140, it is to categorize types of the defect, for determining ifthe defect is a compensable defect. The method for determining if thedefect is a compensable defect is that when a brightness valuecorresponding to a maximum grayscale of the defect and a brightnessvalue corresponding to a minimum grayscale of the defect meet Equation1, the defect is determined as a compensable defect.

$\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where

max denotes to the maximum grayscale of the standard gamma curve of thedefect, min to the minimum grayscale of the standard gamma curve of thedefect, X(max) to the brightness value corresponding to the maximumgrayscale, X(min) to the brightness value corresponding to the minimumgrayscale, and T to a predetermined threshold.

Or if the standard gamma curve of the defect constitutes in crest ortrough, the defect is determined as a compensable defect.

If the defect is determined as a compensable defect, then go to Step150; if the defect is a non-compensable defect, then go to END.

At Step 150, it is to calculate a grayscale compensation value of eachgrayscale of the defect based on the standard gamma curve of the defectand the standard gamma curve of the background of the defect area. Thegrayscale compensation value of each grayscale is calculated based onthe standard gamma curve of the defect and the standard gamma curve ofthe background of the defect area, by Equation 2

Δgray=gray2(L)−gray1(L),where  Equation 2:

gray1(L) denotes to a grayscale of the defect obtained at a particularbrightness value L based on the standard gamma curve of the defect,gray2(L) to a grayscale of the background of the defect area obtained atthe particular brightness value L based on the standard gamma curve ofthe background of the defect area, and Δgray to a grayscale compensationvalue of the grayscale gray1(L) of the defect.

Moreover, it is to be noted that Step 140 is for further reducing amountof calculation according to the grayscale compensation method for thedefect on the display panel according to the embodiment so as to altercalculation efficiency. It is also to be understood that the grayscalecompensation method according to the embodiment can skip Step 140.

FIG. 2 depicts a block diagram of the grayscale compensation system forthe defect on the display panel according to another preferredembodiment of the present invention.

Referring to FIG. 2, the grayscale compensation system comprises: alocation obtaining unit 210, a gamma-curve obtaining unit 220, astandard-gamma-curve obtaining unit 230, a compensable-defectdetermining unit 240, and a calculating unit 250.

In particular, the location obtaining unit 210 is configured to obtainthe set of coordination of the defect on the display panel, and todetermine the defect area where the defect locates based on the set ofcoordination. In more detail, the location obtaining unit 210 obtainsthe brightness value of the defect of the display panel and thebrightness value of the background of the display panel, and thenobtains the location coordinates of the defect on the display panelbased on the brightness value of the defect of the display panel and thebrightness value of the background of the display panel; where thebrightness value of the background of the display panel refers to thebrightness value of the normal area in the display panel, that is thenon-defect area.

The gamma-curve obtaining unit 220 is configured to obtain the gammacurve of the defect, the gamma curve of the background of the defectarea, and the standard gamma curve of the background of the displaypanel. In more detail, the gamma-curve obtaining unit 220 obtains thegamma curve of the defect by obtaining the brightness value of eachgrayscale, where the grayscales of the embodiment are from 0 to 255, 256grayscales in total. The gamma-curve obtaining unit 220 obtains thegamma curve of the defect area by obtaining the brightness value of thebackground of the defect area at each grayscale, where the brightnessvalue of the background of the defect area refers to the brightnessvalue of the area in rest of the defect within the defect area. Thegamma-curve obtaining unit 220 also obtains the standard gamma curve ofthe display panel by obtaining the brightness value of the background ofthe display panel measured by a standard optical measurement device (CA310) at each grayscale.

The standard-gamma-curve obtaining unit 230 is configured to obtain thestandard gamma curve of the defect and the standard gamma curve of thebackground of the defect area, based on the gamma curve of the defect,the gamma curve of the background of the defect area, and the standardgamma curve of the background of the display panel. In more detail, thestandard-gamma-curve obtaining unit 230 obtains the brightness value ofthe defect and the first mapping curve of the brightness value of thebackground of the display panel, and the brightness value of thebackground of the defect area and the second mapping curve of thebrightness value of the background of the display panel based on thegamma curve of the defect, the gamma curve of the background of thedefect area, and the standard gamma curve of the background of thedisplay panel; then the standard-gamma-curve obtaining unit 230 obtainsthe standard gamma curve of the defect and the standard gamma curve ofthe background of the defect area by the first mapping curve and thesecond mapping curve.

To further reduce the amount of calculation according to the grayscalecompensation method for the defect on the display panel according to theembodiment, the compensable-defect determining unit 240 is configured tocategorize types of the defect, for determining if the defect is acompensable defect. In more detail, the compensable-defect determiningunit 240 determines if the brightness value corresponding to the maximumgrayscale of the defect and the brightness value corresponding to theminimum grayscale of the defect meet Equation 1, and accordinglydetermines if the defect a compensable defect.

The compensable-defect determining unit 240 determines the defect as acompensable defect if the brightness value corresponding to the maximumgrayscale of the defect and the brightness value corresponding to theminimum grayscale of the defect meet Equation 1.

Or if the standard gamma curve of the defect constitutes in crest ortrough, the compensable-defect determining unit 240 determines thedefect as a compensable defect.

When the compensable-defect determining unit 240 determines the defectas a compensable defect, the calculating unit 250 calculates thegrayscale-compensation value for each grayscale of the defect byEquation 2, based on the standard gamma curve and the standard gammacurve of the background of the defect area.

In conclusion, it reduces the calculation substantially and achieves thebest compensation to the defect on the display panel for the grayscalecompensation method according to the embodiment and the system of thesame.

Although the present invention has been explained by the embodimentsshown in the drawings described above, it should be understood to theordinary skilled person in the art that the invention is not limited tothe embodiments, but rather various changes or modifications thereof arepossible without departing from the spirit of the invention.Accordingly, the scope of the invention shall be determined only by theappended claims and their equivalents.

What is claimed is:
 1. A method of grayscale compensation to defects ona display panel, comprising: (A) obtaining a set of coordination of thedefect on the display panel, and determining a defect area where thedefect locates based on the set of coordination; (B) obtaining a gammacurve of the defect, a gamma curve of a background of the defect area,and a standard gamma curve of the background of the display panel; (C)obtaining a standard gamma curve of the defect and a standard gammacurve of the background of the defect area, based on the gamma curve ofthe defect, the gamma curve of the background of the defect area, andthe standard gamma curve of the background of the display panel; and (D)calculating a grayscale-compensation value for each grayscale of thedefect, based on the standard gamma curve and the standard gamma curveof the background of the defect area.
 2. The method of claim 1, whereinthe step (C) of obtaining a standard gamma curve of the defect and astandard gamma curve of the background of the defect area comprises:obtaining a first mapping curve of a brightness value of the defect anda brightness value of the background of the display panel, and a secondmapping curve of a brightness value of the background of the defect areaand the brightness value of the background of the display panel, basedon the gamma curve of the defect, the gamma curve of the background ofthe defect area, and the standard gamma curve of the background of thedisplay panel; and obtaining the standard gamma curve of the defect andthe standard gamma curve of the background of the defect area by thefirst mapping curve and the second mapping curve.
 3. The method of claim1, wherein before step (D), the method further comprises: determining ifthe defect is a compensable defect, wherein in case that the defect as acompensable defect, performing step (D).
 4. The method of claim 2,wherein before step (D), the method further comprises: determining ifthe defect is a compensable defect, wherein in case that the defect as acompensable defect, performing step (D).
 5. The method of claim 3,wherein a step of determining if the defect is a compensable defectcomprises: determining the defect as a compensable defect, if abrightness value corresponding to a maximum grayscale of the standardgamma curve of the defect and a minimum grayscale of the standard gammacurve of the defect meet Equation 1 $\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$ where max denotes to the maximum grayscale of the standardgamma curve of the defect, min to the minimum grayscale of the standardgamma curve of the defect, X(max) to the brightness value correspondingto the maximum grayscale, X(min) to the brightness value correspondingto the minimum grayscale, and T to a predetermined threshold.
 6. Themethod of claim 4, wherein a step of determining if the defect is acompensable defect comprises: determining the defect as a compensabledefect, if a brightness value corresponding to a maximum grayscale ofthe standard gamma curve of the defect and a minimum grayscale of thestandard gamma curve of the defect meet Equation 1 $\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$ where max denotes to the maximum grayscale of the standardgamma curve of the defect, min to the minimum grayscale of the standardgamma curve of the defect, X(max) to the brightness value correspondingto the maximum grayscale, X(min) to the brightness value correspondingto the minimum grayscale, and T to a predetermined threshold.
 7. Themethod of claim 1, wherein the step (D) of calculating the grayscalecompensation value of each grayscale based on the standard gamma curveof the defect and the standard gamma curve of the background of thedefect area, is performed by Equation 2Δgray=gray2(L)−gray1(L),  Equation 2: where gray1(L) denotes to agrayscale of the defect obtained at a particular brightness value Lbased on the standard gamma curve of the defect, gray2(L) to a grayscaleof the background of the defect area obtained at the particularbrightness value L based on the standard gamma curve of the backgroundof the defect area, and Δgray to a grayscale compensation value of thegrayscale gray1(L) of the defect.
 8. A grayscale compensation system fora defect on a display panel, comprising: a location obtaining unit,configured to obtain a set of coordination of the defect on the displaypanel, and to determine a defect area where the defect locates based onthe set of coordination; a gamma-curve obtaining unit, configured toobtain a gamma curve of the defect, a gamma curve of a background of thedefect area, and a standard gamma curve of the background of the displaypanel; a standard-gamma-curve obtaining unit, configured to obtain astandard gamma curve of the defect and a standard gamma curve of thebackground of the defect area, based on the gamma curve of the defect,the gamma curve of the background of the defect area, and the standardgamma curve of the background of the display panel; and a calculatingunit, configured to calculate a grayscale-compensation value for eachgrayscale of the defect, based on the standard gamma curve and thestandard gamma curve of the background of the defect area.
 9. Thegrayscale compensation system of claim 8, wherein thestandard-gamma-curve obtaining unit is further configured to obtain afirst mapping curve of a brightness value of the defect and a brightnessvalue of the background of the display panel, and a second mapping curveof a brightness value of the background of the defect area and thebrightness value of the background of the display panel, based on thegamma curve of the defect, the gamma curve of the background of thedefect area, and the standard gamma curve of the background of thedisplay panel; and to obtain the standard gamma curve of the defect andthe standard gamma curve of the background of the defect area by thefirst mapping curve and the second mapping curve.
 10. The grayscalecompensation system of claim 8, wherein the grayscale compensationsystem further comprises: a compensable-defect determining unit,configured to determine if the defect is a compensable defect, whereinin case that the compensable-defect determining unit determines thedefect as a compensable defect, the calculating unit calculates out thegrayscale-compensation value for each grayscale of the compensabledefect based on the standard gamma curve of the compensable defect andthe standard gamma curve of the background of the defect area whereinthe compensable defect located.
 11. The grayscale compensation system ofclaim 9, wherein the grayscale compensation system further comprises: acompensable-defect determining unit, configured to determine if thedefect is a compensable defect, wherein in case that thecompensable-defect determining unit determines the defect as acompensable defect, the calculating unit calculates out thegrayscale-compensation value for each grayscale of the compensabledefect based on the standard gamma curve of the compensable defect andthe standard gamma curve of the background of the defect area whereinthe compensable defect located.
 12. The grayscale compensation system ofclaim 10, wherein the compensable-defect determining unit furtherconfigured to determine the defect as a compensable defect if abrightness value corresponding to a maximum grayscale of the standardgamma curve of the defect and a minimum grayscale of the standard gammacurve of the defect meet Equation 1 $\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$ where max denotes to the maximum grayscale of the standardgamma curve of the defect, min to the minimum grayscale of the standardgamma curve of the defect, X(max) to the brightness value correspondingto the maximum grayscale, X(min) to the brightness value correspondingto the minimum grayscale, and T to a predetermined threshold.
 13. Thegrayscale compensation system of claim 11, wherein thecompensable-defect determining unit further configured to determine thedefect as a compensable defect if a brightness value corresponding to amaximum grayscale of the standard gamma curve of the defect and aminimum grayscale of the standard gamma curve of the defect meetEquation 1 $\begin{matrix}{{\frac{{X\left( \max \right)} - {X\left( \min \right)}}{\max + 1} \geq T},} & {{Equation}\mspace{14mu} 1}\end{matrix}$ where max denotes to the maximum grayscale of the standardgamma curve of the defect, min to the minimum grayscale of the standardgamma curve of the defect, X(max) to the brightness value correspondingto the maximum grayscale, X(min) to the brightness value correspondingto the minimum grayscale, and T to a predetermined threshold.
 14. Thegrayscale compensation system of claim 8, wherein the calculating unitfurther configured to calculate out the grayscale compensation value ofeach grayscale, based on the standard gamma curve of the defect and thestandard gamma curve of the background of the defect area, by Equation 2Δgray=gray2(L)−gray1(L),  Equation 2: where gray1(L) denotes to agrayscale of the defect obtained at a particular brightness value Lbased on the standard gamma curve of the defect, gray2(L) to a grayscaleof the background of the defect area obtained at the particularbrightness value L based on the standard gamma curve of the backgroundof the defect area, and Δgray to a grayscale compensation value of thegrayscale gray1(L) of the defect.